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2003 CRF450R Engine Stutter Problem

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I ride my bike almost every weekend and this past weekend I noticed the engine stuttering under power particularly as I hit the throttle hard going up rough inclines. I changed the plug, drained the gas, added new fuel, and cleaned the air filter, but it is still stuttering as if maybe an electrical problem. I have examined the wiring and see no obvious problem. Any suggestions? This is the first time I have ever had any problems with the engine.

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I ride my bike almost every weekend and this past weekend I noticed the engine stuttering under power particularly as I hit the throttle hard going up rough inclines. I changed the plug, drained the gas, added new fuel, and cleaned the air filter, but it is still stuttering as if maybe an electrical problem. I have examined the wiring and see no obvious problem. Any suggestions? This is the first time I have ever had any problems with the engine.

just try the basics at first, ( if you have an aftermarket flywheel it would be my first suspect , i have had 3 of those screw me and do just what you are talking about !)

but i would drop the needle a clip and try it and see if that helped, then raise it one and so on,----normal jetting stuff.

make sure your ap squirt works.

have you been keeping the motor fresh, or is it way tired ?

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I've owned the bike since it was 3 mos. old and have done routine oil, filter, shock, fork, linkage, tires, chain, sprokets, and slider maintenance, but have never touched the engine, except for changing the spark plug. Everything is set as it came from the factory. No new parts and I have never adjusted the carburator settings. Never had too! It ran perfectly up until now. It still runs strong most everywhere except when hard on the power on rough uphill inclines. My old 97 CR250 did something similar to this, but the stuttering was more frequent. It turned out to be a broken wire to the ignition module. That's why I thought it might be something electrical.

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I bought it in 04. Haven't rebuilt it yet or checked valves, because I was told 4-strokes don't require anywhere near the maintenance of a 2-stroke. I used to rebuild my 2-stroke about every 1 1/2 years. That's for a person who rides on average 3-4 times per month. I figured it was probably about due. Maybe past due--right??

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I bought it in 04. Haven't rebuilt it yet or checked valves, because I was told 4-strokes don't require anywhere near the maintenance of a 2-stroke. I used to rebuild my 2-stroke about every 1 1/2 years. That's for a person who rides on average 3-4 times per month. I figured it was probably about due. Maybe past due--right??

:thumbsup::thumbsup:

Not these 4strokes. Maybe XRs. These race bikes need a lot of maintenece. You should check your valves every 25-40 hrs. Rebuild top end no more than 130 hrs. I do my top end every 80-100 hrs., and I thought I was bad. Do a search about valves issues and such in the crf450r forum.

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I want to thank all of you who responded to my request for assistance. I will try cleaning the carb and jets. Will also read about the valves and buy parts for a top end job. Any other suggestions are welcomed.

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